U.S. patent application number 10/532995 was filed with the patent office on 2006-07-27 for resin composition for coating electric wire and electric wire using the same.
Invention is credited to Makoto Katsumata, Hitoshi Ushijima, Shinichi Watanabe, Kiyoshi Yagi.
Application Number | 20060167158 10/532995 |
Document ID | / |
Family ID | 32211628 |
Filed Date | 2006-07-27 |
United States Patent
Application |
20060167158 |
Kind Code |
A1 |
Yagi; Kiyoshi ; et
al. |
July 27, 2006 |
Resin composition for coating electric wire and electric wire using
the same
Abstract
In a resin composition to be used for electric wire sheaths, in
which a polyolefin resin and an ultrafine nylon fibers-dispersed
polyolefin resin composition are mixed, a blend ratio of a
polyolefin (PO) and ultrafine nylon fibers (Ny) in the ultrafine
nylon fibers-dispersed polyolefin resin composition preferably
falls within a range from 5:5 to 9:1 (PO:Ny). It is further
preferable that the blend ratio is 8:2. The resin composition may
be comprised of at least one of silica particles and magnesium
hydroxide particles.
Inventors: |
Yagi; Kiyoshi; (Susono-shi,
JP) ; Katsumata; Makoto; (Susono-shi, JP) ;
Ushijima; Hitoshi; (Susono-shi, JP) ; Watanabe;
Shinichi; (Susono-shi, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Family ID: |
32211628 |
Appl. No.: |
10/532995 |
Filed: |
October 28, 2003 |
PCT Filed: |
October 28, 2003 |
PCT NO: |
PCT/JP03/13791 |
371 Date: |
November 18, 2005 |
Current U.S.
Class: |
524/436 ;
524/514 |
Current CPC
Class: |
C08L 77/00 20130101;
C08L 23/06 20130101; C08K 3/22 20130101; C08L 2205/02 20130101;
C08L 2205/16 20130101; H01B 3/47 20130101; C08K 5/0066 20130101;
C08L 23/06 20130101; C08L 2203/202 20130101; C08K 9/06 20130101;
C08L 23/06 20130101; C08L 51/06 20130101; H01B 3/441 20130101; C08L
2666/20 20130101; C08L 2201/02 20130101; C08L 2666/02 20130101 |
Class at
Publication: |
524/436 ;
524/514 |
International
Class: |
C08K 3/22 20060101
C08K003/22; C08L 77/00 20060101 C08L077/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 29, 2002 |
JP |
2002-314845 |
Claims
1. A resin composition to be used for electric wire sheaths,
wherein a polyolefin resin and an ultrafine nylon fibers-dispersed
polyolefin resin composition are mixed.
2. The resin composition as set forth in claim 1, wherein a blend
ratio of a polyolefin (PO) and ultrafine nylon fibers (Ny) in the
ultrafine nylon fibers-dispersed polyolefin resin composition falls
within a range from 5:5 to 9:1 (PO:Ny).
3. The resin composition as set forth in claim 2, wherein the blend
ratio is 8:2 (PO:Ny).
4. The resin composition as set forth in claim 1, further
comprising at least one of silica particles and magnesium hydroxide
particles.
5. The resin composition as set forth in claim 1, wherein the
ultrafine nylon fibers-dispersed polyolefin resin composition is
comprised of a polyolefin, polyamide fibers, a silane coupling
agent and silica particles.
6. The resin composition as set forth in claim 5, wherein the
polyamide fibers are comprised of at least one of silica particles
and magnesium hydroxide particles.
7. The resin composition as set forth in claim 1, wherein a mean
fiber diameter of the polyamide fibers is not greater than 5 .mu.m,
and an aspect ratio thereof falls within a range from 20 to
1000.
8. An electric wire, comprising a sheath comprised of the resin
composition as set forth in claim 1.
Description
TECHNICAL FIELD
[0001] This invention relates to a resin composition for electric
wire sheaths and an electric wire using the same.
DESCRIPTION OF BACKGROUND ART
[0002] The use of electric wires has recently been increasing with
the advanced performance and sophistication of electrical
components for motor vehicles. An electrical conductor, such as
copper, having its periphery covered with a polyvinyl chloride
resin has hitherto been widely used as such an insulated electric
wire. The electric wire using a polyvinyl chloride resin has the
advantage of being low in production cost, while its wear
resistance, flexibility, withstanding voltage and insulation
resistance are relatively high. Moreover, the polyvinyl chloride
resin composition is itself excellent in flame retardancy.
[0003] However, as the polyvinyl chloride resins produce harmful
halogen gas when burning and thereby contaminate the global
environment, a search for their substitute or non-halogen materials
has been under way.
[0004] Thus, attempts have recently been made to use an olefin
resin composition, such as polyethylene, as an insulator not
containing any halide, and as an insulator for electric wires in a
place generating a high temperature, such as a wire harness in a
motor vehicle (see, for example, Japanese Patent Publication No.
9-95566A, page 2).
[0005] The electric wires used for a wire harness in a motor
vehicle, etc. are identified by coloring in specific colors (red,
white, black, blue, green, etc.) for facilitating wiring and
connection. The coloring of electric wires has hitherto been
carried out by one of the following methods (1) to (3): [0006] (1)
Not only the surface of the sheath layer but also the inside
thereof is uniformly colored by kneading dye or pigment into the
insulative resin when the extrusion molding of the insulative resin
is performed; [0007] (2) A colored resin film is laminated on the
conductor, and a translucent insulative resin is coated by the
extrusion molding; and [0008] (3) The conductor is covered with an
insulative resin by the extrusion molding, and organic
solvent-family ink is applied on the surface of the sheath
layer.
[0009] However, in the method (1), the productivity is low because
the manufacturing line may be frequently stopped when the color is
changed. Electric wires which are colored with rare colors may be
in stock. In the method (2), it is difficult to surely distinguish
colors through the translucent insulative resin coating, so that
the wiring or connecting workability is low. In the method (3), a
capital investment is necessary to provide a good working
environment for using the organic solvent-family ink, thereby
increasing the manufacturing cost.
[0010] In view of such circumstances, it is proposed that the
insulative layer of the electric wire is colored by water-soluble
ink containing a polyamine, alcohol, and pigment with predetermined
ratios (see Japanese Patent Publication No. 10-251563A, page
2).
[0011] However, the water-soluble ink cannot provide a good
colorability when the surface comprised of a polyolefin resin
component.
SUMMARY OF THE INVENTION
[0012] It is therefore an object of the invention to provide a
resin component to be used for electric wire sheaths which is
excellent in flexibility, elasticity, dye-colorability, mechanical
properties, and wear resistance, and to provide an electric wire
using such a resin component.
[0013] In order to achieve the above object, according to the
invention, there is provided a resin composition to be used for
electric wire sheaths, wherein a polyolefin resin and an ultrafine
nylon fibers-dispersed polyolefin resin composition are mixed.
[0014] Preferably, a blend ratio of a polyolefin (PO) and ultrafine
nylon fibers (Ny) in the ultrafine nylon fibers-dispersed
polyolefin resin composition falls within a range from 5:5 to 9:1
(PO:Ny). Here, it is preferable that the blend ratio is 8:2
(PO:Ny).
[0015] Preferably, the resin composition further comprises at least
one of silica particles and magnesium hydroxide particles.
[0016] Preferably, the ultrafine nylon fibers-dispersed polyolefin
resin composition is comprised of a polyolefin, polyamide fibers, a
silane coupling agent and silica particles.
[0017] Here, the polyamide fibers are comprised of at least one of
silica particles and magnesium hydroxide particles.
[0018] Preferably, a mean fiber diameter of the polyamide fibers is
not greater than 5 .mu.m, and an aspect ratio thereof falls within
a range from 20 to 1000.
[0019] According to the invention, there is also provided an
electric wire, comprising a sheath comprised of the above resin
composition.
[0020] In the invention, the tensile elongation (that is,
flexibility and elasticity) and the ink colorability are enhanced
by mixing the polyolefin resin and the ultrafine nylon
fibers-dispersed polyolefin resin composition. Further, the wear
resistance and the dye colorability are enhanced by containing the
silica particles, the magnesium hydroxide particles, or a mixture
of those particles.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a perspective view showing an electric wire for
vehicle according to a first embodiment (single wire) of the
invention;
[0022] FIG. 2 is a perspective view showing an electric wire for
vehicle according to a second embodiment (flat wire) of the
invention;
[0023] FIG. 3 is a perspective view showing an electric wire for
vehicle according to a third embodiment (shielded wire) of the
invention;
[0024] FIG. 4 is a schematic view for explaining how to perform a
scrape wear test; and
[0025] FIG. 5 is a schematic view for explaining how to perform a
flame retardancy test.
BEST MODE FOR CARRYING OUT THE INVENTION
[0026] There will be described below in detail resin composition
for electric wire sheaths and an electric wire according to
preferred embodiments of the invention.
[0027] Not specifically defined, the polyolefin resin to be used in
the resin composition for electric wire sheaths is preferably one
having a melting point that falls between 80 and 250.degree. C.
Preferred examples of the resin of the type are a homopolymer and a
copolymer of olefin having from 2 to 8 carbon atoms, a copolymer of
olefin having from 2 to 8 carbon atoms with vinyl acetate, a
copolymer of olefin having from 2 to 8 carbon atoms with acrylic
acid or its ester, a copolymer of olefin having from 2 to 8 carbon
atoms with methacrylic acid or its ester, and a copolymer of olefin
having from 2 to 8 carbon atoms with a vinylsilane compound.
[0028] Specific examples of the resin are high-density
polyethylene, low-density polyethylene, linear low-density
polyethylene, polypropylene, ethylene/propylene block copolymer,
ethylene/propylene random copolymer, poly-4-methylpentene-1, -
polybutene-1, polyhexene-1, ethylene/vinyl acetate copolymer,
ethylene/vinyl alcohol copolymer, ethylene/acrylic acid copolymer,
ethylene/methyl acrylate copolymer, ethylene/ethyl acrylate
copolymer, ethylene/propyl acrylate copolymer, ethylene/butyl
acrylate copolymer, ethylene/2-ethylhexyl acrylate copolymer,
ethylene/hydroxyethyl acrylate copolymer,
ethylene/vinyltrimethoxysilane copolymer,
ethylene/vinyltriethoxysilane copolymer, ethylene/vinylsilane
copolymer. Also preferred for use herein are halogenopolyolefins
such as polyethylene chloride, polyethylene bromide,
chlorosulfonated polyethylene.
[0029] Of those, especially preferred are high-density polyethylene
(HDPE), low-density polyethylene (LDPE), linear low-density
polyethylene (LLDPE), polypropylene (PP), ethylene/propylene block
copolymer (EPBC), ethylene/propylene random copolymer (EPRC),
ethylene/vinyl acetate copolymer (EVA), ethylene/ethyl acrylate
copolymer (EEA), and ethylene/vinyl alcohol copolymer; and most
preferred are those having a melt flow index (MFI) that falls
between 0.2 and 50 g/10 min. One or more of these may be used
herein either singly or as combined.
[0030] Next, there will be described ultrafine nylon
fibers-dispersed polyolefin resin composition to be used in the
resin composition of the invention.
[0031] Also not specifically defined, the nylon component in the
nylon fiber to be used in the ultrafine nylon fibers-dispersed
polyolefin resin composition (hereinafter, simply referred as
"Ny-PO") is a thermoplastic polyamide having an amide group in the
backbone chain thereof (this is hereinafter referred to as
"polyamide") and having a melting point that falls between 135 and
350.degree. C. and is higher by at least 20.degree. C. than the
melting point of the polyolefin. Preferably, the polyamide has a
melting point falling between 160 and 265.degree. C. Also,
preferably, the polyamide of the type may give tough fibers through
extrusion and stretching.
[0032] Specific examples of the polyamide are nylon 6, nylon 66,
nylon 6-nylon 66 copolymer, nylon 610, nylon 46, nylon 11, nylon
12, nylon MXD6, xylylenediamine/adipic acid polycondensate,
xylylenediamine/pimelic acid polycondensate,
xylylenediamine/suberic acid polycondensate,
xylylenediamine/azelaic acid polycondensate,
xylylenediamine/sebacic acid polycondensate,
tetramethylenediamine/terephthalic acid polycondensate,
hexamethylenediamine/terephthalic acid polycondensate,
octamethylenediamine/terephthalic acid polycondensate,
trimethylhexamethylenediamine/terephthalic acid polycondensate,
decamethylenediamine/terephthalic acid polycondensate,
undecamethylenediamine/terephthalic acid polycondensate,
dodecamethylenediamine/terephthalic acid polycondensate,
tetramethylenediamine/isophthalic acid polycondensate,
hexamethylenediamine/isophthalic acid polycondensate,
octamethylenediamine/isophthalic acid polycondensate,
trimethylhexamethylenediamine/isophthalic acid polycondensate,
decamethylenediamine/isophthalic acid polycondensate,
undecamethylenediamine/isophthalic acid polycondensate, and
dodecamethylenediamine/isophthalic acid polycondensate.
[0033] Of those polyamides, especially preferred examples are nylon
6 (PA6), nylon 66 (PA66), nylon 12 (PA12), nylon 6-nylon 66
copolymer. One or more of these may be used herein. Preferably,
these polyamides have a molecular weight falling between 10,000 and
200,000.
[0034] The fiber diameter of the nylon fiber is not specifically
limited, but may be 5 .mu.m or less.
[0035] The polyolefin used in the ultrafine nylon fibers-dispersed
polyolefin resin composition is the same polyolefin as has been
mentioned as the principal component of the resin composition
described before.
[0036] The weight ratio of the polyolefin resin (PO) and very fine
nylon fibers (Ny) in the Ny-PO used according to this invention is
not specifically limited, but may be preferably 5:5 to 9:1 (PO:Ny),
more preferably 7:3 to 9:1 (PO:Ny), and most preferably 8:2
(PO:Ny).
[0037] The amount of Ny-PO used in the resin composition according
to this invention is not specifically limited, but may be
preferably 100 parts by weight or less, more preferably 50 parts by
weight or less, and still more preferably 5 to 20 parts by weight
for 100 parts by weight of the resin composition.
[0038] Moreover, the resin composition according to this invention
preferably contains silica particles or magnesium hydroxide
particles or a mixture of those particles to improve the wear
resistance and coloring property of a molded resin product obtained
from the resin composition.
[0039] The silica particles which the resin composition according
to this invention may contain (including those subjected to surface
treatment by a surface treating agent, or treating method, such as
coupling or CVD method) are not specifically limited, but may have
a particle diameter of preferably 1 nm to 100 .mu.m, and
particularly preferably 1 nm to 100 nm.
[0040] The magnesium hydroxide particles which the resin
composition according to this invention may contain (including
those subjected to surface treatment by a surface treating agent,
or treating method, such as coupling or CVD method) are not
specifically limited, but may have a particle diameter of
preferably 1 nm to 100 .mu.m, particularly preferably 10 nm to 10
.mu.m, and still more preferably 10 nm to 1000 nm.
[0041] The amount of the silica or magnesium hydroxide particles or
a mixture of those particles which the resin composition according
to this invention may contain is not specifically limited, but may
be 100 parts by weight or less, more preferably 60 parts by weight
or less, and still more preferably 10 to 30 parts by weight for 100
parts by weight of the resin composition.
[0042] Moreover, it is possible to use in the resin composition
according to this invention a ultrafine nylon fibers-dispersed
polyolefin resin composition (Ny-PO) containing a polyolefin,
polyamide fibers, a silane coupling agent and silica or magnesium
hydroxide particles or a mixture of those particles. The use of
such Ny-PO makes it possible to improve the wear resistance of the
resin composition according to this invention to a further
extent.
[0043] Such Ny-PO may be of the polyamide fibers containing or not
containing silica or magnesium hydroxide particles or a mixture of
those particles.
[0044] The polyolefin used in the Ny-PO containing a polyolefin,
polyamide fibers, a silane coupling agent and silica or magnesium
hydroxide particles or a mixture of those particles is not
specifically limited, but may be the same polyolefin as has been
mentioned as the principal component of the resin composition
described before.
[0045] The polyamide used in the above Ny-PO is not specifically
limited, but may be the same as has been mentioned as the nylon
component of the resin composition described before.
[0046] The silane coupling agent is preferably employed in an
amount of from 0.1 to 5.5 parts by weight and more preferably from
0.2 to 3.0 parts by weight, based on 100 parts by weight of a total
amount of the polyolefin and polyamide (or more specifically, from
0.1 to 8 parts by weight and more preferably from 0.2 to 4 parts by
weight when silica or magnesium hydroxide particles or a mixture of
those particles are added simultaneously; and from 0.1 to 5.5 parts
by weight when silica or magnesium hydroxide particles or a mixture
of those particles are added later; and silane coupling treatment
to silica). If the amount of the silane coupling agent is smaller
than 0.1 part by weight, there is not obtained any composition
having high wear resistance, high flame retardancy and high
strength, and if it is larger than 5.5 parts by weight, there is
not obtained any composition having a high elastic modulus. If the
amount of the silane coupling agent is smaller than 0.1 part by
weight, there is obtained only a composition of low strength, since
no strong bond is formed among the polyolefin, polyamide and silica
particles. If it is larger than 5.5 parts by weight, there is
obtained only a composition having a low elastic modulus, since the
polyamide does not form satisfactorily fine fibers.
[0047] An organic peroxide may be used together with the silane
coupling agent. When an organic peroxide is used together with it,
then radicals may be formed in the molecular chains of the
polyolefin component and they may react with the silane coupling
agent to promote the reaction of the polyolefin component and the
silane coupling agent. The amount of the organic peroxide to be
used may be from 0.01 to 1.0 part by weight relative to 100 parts
by weight of the polyolefin component. Preferably, the temperature
for the half-life period for one minute of the organic peroxide is
the same as the higher one of the melting point of the polyolefin
component or the melting point of the silane coupling agent or is
higher by around 30.degree. C. than that temperature. Concretely,
the temperature for the half-life period for one minute of the
organic peroxide preferably falls between 110 and 200.degree. C. or
so.
[0048] Specific examples of the organic peroxide are di-x-cumyl
peroxide, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane,
1,1-di-t-butylperoxycyclohexane, 2,2-di-t-butylperoxybutane,
n-butyl 4,4-di-t-butylperoxyvalerate,
2,2-bis(4,4-di-t-butylperoxycyclohexane)propane,
2,2,4-trimethylpentylperoxy neodecanoate, x-cumylperoxy
neodecanoate, t-butylperoxy neohexanoate, t-butylperoxy pivalate,
t-butylperoxy acetate, t-butylperoxy laurate, t-butylperoxy
benzoate, t-butylperoxy isophthalate. Above all, preferred are
those of which the temperature for the half-life period for one
minute falls between a temperature at which the components are
melt-kneaded and a temperature higher by around 30.degree. C. than
the melt-kneading temperature, concretely the temperature for the
half-life period for one minute thereof preferably falls between 80
and 260.degree. C., approximately.
[0049] The silica particles, the magnesium hydroxide particles or
the mixture of those particles to be used in the Ny-PO are not is
not specifically limited, but may be the same as have. been
mentioned as the silica particles, the magnesium hydroxide
particles or a mixture of those particles of the resin composition
described before.
[0050] Also not specifically defined, the content of the silica
particles, the magnesium hydroxide particles or the mixture of
those particles to be in the Ny-PO is preferably from 1 to 100
parts by weight, more preferably from 1 to 60 parts by weight
relative to 100 parts by weight of the polyolefin resin
composition.
[0051] If the amount is greater than 60 parts by weight, the
strength of the composition could not high.
[0052] If, on the other hand, the amount is less than 1 part by
weight, the hydrogen bond part between the silane coupling agent
and the silica particles, the magnesium hydroxide particles or the
mixture of those particles will be unsatisfactory and the
composition could not also have the intended abrasion resistance
and strength.
[0053] In fact, however, the preferred amount of the silica
particles, the magnesium hydroxide particles or the mixture of
those particles varies depending on the kneading condition in
preparing the polyolefin resin composition of the invention, and
therefore it may be suitably determined before the constituent
components are kneaded.
[0054] Almost all of the polyamide component in the Ny-PO forms
fine fibers that are uniformly dispersed in the matrix of the
composition. Concretely, at least 70% by weight, preferably at
least 80% by weight, more preferably at least 90% by weight of the
polyamide component forms fine fibers that are uniformly dispersed
in the matrix. Preferably, the mean fiber diameter of the polyamide
component fibers is at most 1 .mu.m, and the mean fiber length
thereof is at most 100 .mu.m. Also preferably, the aspect ratio
(ratio of fiber length/fiber diameter) of the fibers falls between
20 and 1,000. The polyolefin component bonds to the polyamide
component at their interface.
[0055] Next, there will be described a method for producing the
Ny-PO containing the polyolefin, the polyamide fibers, the silica
coupling agent, and the silica particles, the magnesium hydroxide
particles or the mixture of those particles as described the above.
The method for producing the Ny-PO includes the following two ways.
[0056] (A) A resin composition that comprises a polyolefin,
polyamide fibers and a silane coupling agent is previously prepared
and this is kneaded with silica particles. [0057] (B) A polyolefin,
a polyamide, a silane coupling agent and silica particles are
kneaded.
[0058] Though not specifically defined, the method for preparing
the resin composition that comprises a polyolefin, polyamide fibers
and a silane coupling agent in the mode (A) comprises, for example,
the following steps: [0059] (A1) melt-kneading a polyolefin
(component 1) and a silane coupling agent (component 2) to
chemically modify the component 1; [0060] (A2) melt-kneading a
polyamide (component 3) with the component 1 that has been
chemically modified with the component 2, at a temperature not
lower than the melting point of the component 3; [0061] (A3)
melt-kneading, chemically modifying and extruding the polyamide
component 3 with the component 1 that has been chemically modified
with the component 2 at a temperature not lower than the melting
point of the component 3; [0062] (A4) stretching or rolling the
melt-kneaded and chemically-modified extrudate at a temperature not
lower than the melting point of the component 1 but not higher than
the melting point of the component 3 with drafting it; [0063] (A5)
cooling the stretched or rolled composition to room temperature and
pelletizing it; and [0064] (A6) optionally adding a remaining
polyolefin component 1 to the pellets, and further melt-kneading it
at a temperature not higher than the melting point of the component
3, cooling and pelletizing it.
[0065] Step (A1) will be described below. The melt-kneading
temperature is not lower than the melting point of the component 1,
but preferably higher by 30.degree. C. than the melting point. When
the two are melt-kneaded at a temperature higher by 30.degree. C.
than the melting point of the component 1, then the component 1
reacts with the component 2 and is chemically modified by the
component 2. Melt-kneading them may be effected in any ordinary
device generally used for kneading resin or rubber. The device
includes, for example, Banbury mixer, kneader, kneader extruder,
open roll, single-screw kneader, double-screw kneader. Of those
devices, most preferred is a double-screw kneader as it may achieve
continuous melt-kneading within a short period of time (the same
shall apply to the steps mentioned below).
[0066] Step (A2) will be described below. The melt-kneading
temperature is not lower than the melting point of the component 3,
but preferably higher by 10.degree. C. than the melting point. If
the melt-kneading temperature is lower than the melting point of
the component 3, the components could not be kneaded and could not
be fibrously dispersed. Therefore, they are melt-kneaded at a
temperature higher than the melting pint, especially preferably
higher by 20.degree. C. than the melting point of the component
3.
[0067] Step (A3) will be described below. The kneaded mixture
obtained in the step is extruded out through a spinneret or through
an inflation die or T-die. Spinning and extruding the mixture must
be effected at a temperature higher than the melting point of the
component 3. Concretely, it is desirable that the operation is
effected at a temperature higher by 30.degree. C. than the melting
point of the component 3. Even when the operation of melt-kneading
the mixture is effected at a temperature lower than the melting
point of the component 3, the kneaded mixture could not have a
structure of fine fibers of the component 3 dispersed in the matrix
of the component 1. Accordingly, even when the kneaded mixture of
the type is spun and stretched, the component 3 could not form fine
fibers.
[0068] Step (A4) will be described below. The extruded, string-like
or yarn-like product is continuously cooled, stretched or rolled.
Cooling the fibrous product followed by stretching or rolling it is
effected at a temperature lower by 10.degree. C. than the melting
point of the component 3. Stretching and rolling it gives tougher
fibers, and the treatment is favorable since the fiber-reinforced
resin composition thus produced may have better properties. The
stretching or rolling treatment may be effected, for example, by
extruding the kneaded mixture through a spinneret to spin it into a
string-like or yarn-like product, followed by winding it around a
bobbin with drafting. If desired, it may be pelletized into
pellets. Drafting the fibrous product as referred to herein means
that the winding-up speed of the product is higher than the speed
thereof that passes through a spinneret. Preferably, the ratio of
winding-up speed/spinneret speed (draft ratio) falls between 1.5
and 100, more preferably between 2 and 50, even more preferably
between 3 and 30.
[0069] Step (A5) will be described below. The polyamide
fiber-reinforced polyolefin resin composition is preferably in the
form of pellets since any additional resin or rubber component may
be added to and uniformly kneaded with them. The pelletized resin
composition may be uniformly kneaded with such additional rubber or
resin, and it may readily give a polyamide fiber-reinforced resin
composition with fine fibers uniformly dispersed therein.
[0070] Though described separately hereinabove, the respective
steps may be combined into one continuous process to be effected in
a double-screw kneader having a plurality of supply ports each
feeding one of the respective components and a peroxide or the like
into the kneader and having a plurality of kneading zones each
correspond to one of the supply ports. Comprising the thus-combined
steps, the process is more economical, stable and safe.
[0071] The method of kneading the resin composition that comprises
a polyolefin, polyamide fibers and a silane coupling agent, with
silica particles, the magnesium hydroxide particles or the mixture
of those particles is not specifically defined. For example,
pellets of the resin composition that comprises a polyolefin,
polyamide fibers and a silane coupling agent (component 4) may be
thermally kneaded with silica particles, magnesium hydroxide
particles or the mixture of those particles, (component 5) in a
Banbury mixer, kneader, kneader extruder, open roll, single-screw
kneader or double-screw kneader, at a temperature higher by
10.degree. C. than the melting point of polyolefin but not higher
than the melting point of polyamide.
[0072] It is presumed that a hydrogen bond may be formed between
the component 5 and the silane coupling agent in the component 4
through the thermal kneading operation as above. The
thermally-kneaded mixture is preferably extruded, stretched or
rolled, and pelletized.
[0073] The method of producing the Ny-PO that comprises a
polyolefin, polyamide fibers, a silane coupling agent and silica
particles, magnesium hydroxide particles or a mixture of those
particles in the production mode (B) is not specifically defined.
For example, it comprises the following steps: [0074] (B1)
melt-kneading, chemically modifying a polyolefin (component 1) with
a silane coupling agent (component 2); [0075] (B2) melt-kneading a
polyamide (component 3), silica particles, magnesium hydroxide
particles or a mixture of those particles (component 5) with the
component 1 that has been chemically modified with the component 2,
at a temperature not lower than the melting point of the component
3; [0076] (B3) melt-kneading, chemically modifying and extruding
the polyamide component 3 with the component 1 that has been
chemically modified with the component 2 at a temperature not lower
than the melting point of the component 3; [0077] (B4) stretching
or rolling the melt-kneaded and chemically-modified extrudate at a
temperature not lower than the melting point of the component 1 but
not higher than the melting point of the component 3 with drafting
it; [0078] (B5) cooling the stretched or rolled composition to room
temperature and pelletizing it; and [0079] (B6) optionally adding a
remaining polyolefin component 1 to the pellets, and further
melt-kneading it at a temperature not higher than the melting point
of the component 3, cooling and pelletizing it.
[0080] Step (B1) will be described below. The melt-kneading
temperature is not lower than the melting point of the component 1,
but preferably higher by 30.degree. C. than the melting point. When
the components are melt-kneaded at a temperature higher by
30.degree. C. than the melting point of the component 1, then the
component 1 reacts with the component 2 and is chemically modified
by the component 2. Melt-kneading them may be effected in any
ordinary device generally used for kneading resin or rubber. The
device includes, for example, Banbury mixer, kneader, kneader
extruder, open roll, single-screw kneader, double-screw kneader. Of
those devices, most preferred is a double-screw kneader as it may
achieve continuous melt-kneading within a short period of time (the
same shall apply to the steps mentioned below).
[0081] Step (B2) will be described below. The melt-kneading
temperature is not lower than the melting point of the component 3,
but preferably higher by 10.degree. C. than the melting point. If
the melt-kneading temperature is lower than the melting point of
the component 3, the components could not be kneaded and could not
be fibrously dispersed. Therefore, they are melt-kneaded at a
temperature higher than the melting pint, especially preferably
higher by 20.degree. C. than the melting point of the component
3.
[0082] Step (B3) will be described below. The kneaded mixture
obtained in the step is extruded out through a spinneret or through
an inflation die or T-die. Spinning and extruding the mixture must
be effected at a temperature higher than the melting point of the
component 3. Concretely, it is desirable that the operation is
effected at a temperature higher by 30.degree. C. than the melting
point of the component 3. Even when the operation of melt-kneading
the mixture is effected at a temperature lower than the melting
point of the component 3, the kneaded mixture could not have a
structure of fine fibers of the component 3 dispersed in the matrix
of the component 1. Accordingly, even when the kneaded mixture of
the type is spun and stretched, the component 3 could not form fine
fibers.
[0083] Step (B4) will be described below. The extruded, string-like
or yarn-like product is continuously cooled, stretched or rolled.
Cooling the fibrous product followed by stretching or rolling it is
effected at a temperature lower by 10.degree. C. than the melting
point of the component 3. Stretching and rolling it gives tougher
fibers, and the treatment is favorable since the fiber-reinforced
resin composition thus produced may have better properties. The
stretching or rolling treatment may be effected, for example, by
extruding the kneaded mixture through a spinneret to spin it into a
string-like or yarn-like product, followed by winding it around a
bobbin with drafting. If desired, it may be pelletized into
pellets. Drafting the fibrous product as referred to herein means
that the winding-up speed of the product is higher than the speed
thereof that passes through a spinneret. Preferably, the ratio of
winding-up speed/spinneret speed (draft ratio) falls between 1.5
and 100, more preferably between 2 and 50, even more preferably
between 3 and 30.
[0084] Step (B5) will be described below. The polyamide
fiber-reinforced polyolefin resin composition is preferably in the
form of pellets since any additional resin or rubber component may
be added to and uniformly kneaded with them. The pelletized resin
composition may be uniformly kneaded with such additional rubber or
resin, and it may readily give a polyamide fiber-reinforced resin
composition with fine fibers uniformly dispersed therein.
[0085] Though described separately hereinabove, the respective
steps may be combined into one continuous process to be effected in
a double-screw kneader having a plurality of supply ports each
feeding one of the respective components and a peroxide or the like
into the kneader and having a plurality of kneading zones each
corresponding to one of the supply ports. Comprising the
thus-combined steps, the process is more economical, stable and
safe.
[0086] Thermally kneaded in the manner as above, the component 1
reacts with the component 2 and is thereby chemically modified with
the latter, and fine fibers of the component 3 are dispersed in the
matrix of the component 1. As the case may be, whisker fibers of
the component 1 that are finer than the fine fibers of the
component 3 may be formed on the surfaces of the fibers of the
component 3. In this embodiment, the component 3 is also modified
with the component 2. It is presumed that the component 5 may
chemically bond to the component 1 and the component 3 at their
parts that have been chemically modified with the component 2 to
thereby partially crosslink the component 1 and the component 3.
The gel fraction of this embodiment with the component 5 added
thereto is higher than that of the other case not containing the
component 5. To that effect, the component 5 improve various
properties of the resin composition.
[0087] As regards a method for obtaining the resin composition
according to this invention, there is no specific limitation, but
it is possible to mention, for example, a method in which a
polyolefin resin and Ny-PO, and also silica or magnesium hydroxide
particles or a mixture of those particles are pre-blended by using
a high-speed mixing device, such as a Henschel mixer, and are
thereafter kneaded by using a known kneading machine, such as a
single-screw extruder, a double-screw extruder, a Banbary mixer, a
kneader or a roll mill.
[0088] The resin composition according to this invention may
further contain various kinds of auxiliary components which are
usually incorporated, for example, any of various kinds of
oxidation inhibitors, such as of the phenol, phosphorus or sulfur
type, a nucleating agent, an antistatic agent, a metal fatty acid
salt, a lubricant such as of the amide, silicone or Teflon type, a
slip agent, a processing aid, a metal inactivating agent, an
ultraviolet inhibitor, and a filler such as carbon black, white
carbon, calcium carbonate, magnesium silicate, ferrite, zeolite,
montmorillonite, barium sulfate, clay, talc or zinc white, to the
extent not injuring the effects of this invention.
[0089] This invention also provides an electric wire for which the
above resin composition is employed as an insulating material.
There is no limitation to the kind or structure of the electric
wire, but the use of the above resin composition as an insulator
for, for example, a single wire as shown in FIG. 1, a flat wire as
shown in FIG. 2 or a shielded wire as shown in FIG. 3 makes it
possible to achieve a satisfactory improvement in flexibility and
softness, dye coloring property and also wear resistance. In the
drawing, reference numeral 1 denotes a conductor, 2 denotes an
insulator, 3 denotes a braided shield, and 4 denotes a sheath.
[0090] There is no limitation as to a method for forming an
insulator on an electric wire, either, but various known methods
can be employed. For example, an extruder may be a single-screw
extruder having a cylinder diameter of 20 to 90 mm and an L/D of 10
to 40, and having a screw, a crosshead, a breaker grate, a
distributor, a nipple and dice. The above resin composition is
charged into the single-screw extruder set at a temperature
allowing the resin composition to melt thoroughly. The resin
composition is melted and kneaded by the screw, and a specific
amount thereof is supplied to the crosshead via the breaker plate.
The molten resin composition is caused by the distributor to flow
in onto the circumference of the nipple. The resin composition
which has flown in is extruded by the dice onto the circumference
of the conductor in a state coating it, whereby an electric wire
having an insulator is obtained.
[0091] Specific numerical examples will now be described, but this
invention is not limited thereto. TABLE-US-00001 TABLE 1 sample No.
1 2 3 4 composition of low-density polyethylene 100 100 100 100
materials bromine-containing flame retardant 35 35 10 additive 2 2
2 2 Ny-PO (Ny wt %) 10 (2) 10 (2) 10 (2) 10 (2) silica particles 16
nm 10 5 magnesium hydroxide particles 80 nm 60 5 electron-beam
crosslinking (Present or Absent) A A A A properties of tensile
strength (MPa) 11.5 12.5 11.0 11.5 electric wire elongation (%) 540
540 350 330 wear resistance (number of times) 150 210 120 140 flame
retardancy (sec) 5 5 6 12 colorability before coloring 225 225 220
220 25.degree. C. 210 200 200 200 60.degree. C. 170 160 150 150
sample No. (c: comparative) 5 6 c1 c2 composition of low-density
polyethylene 100 100 100 100 materials bromine-containing flame
retardant 35 35 35 35 additive 2 2 2 2 Ny-PO (Ny wt %) 10 (2) 10
(2) silica particles 16 nm 10 10 magnesium hydroxide particles 80
nm electron-beam crosslinking (Present or Absent) P P P P
properties of tensile strength (MPa) 11.5 12.2 10.1 9.7 electric
wire elongation (%) 410 405 410 390 wear resistance (number of
times) 235 260 160 195 flame retardancy (sec) 4 3 6 6 colorability
before coloring 230 230 235 230 25.degree. C. 220 215 230 225
60.degree. C. 195 185 215 205
[0092] [Evaluation for Extrusion Torque]
[0093] Each resin composition composed of the components as shown
in Table 1 was charged into an electric wire extruder (.phi.60 mm,
L/D=24.5, FF screw) and extruded onto a conductor having a
conductor area of 0.5387 mm.sup.2 at an extruding speed of 600
mm/min. and an extruding temperature of 200.degree. C. to make an
electric wire having a finished outside diameter of 1.50 mm.
[0094] The numerical unit for the composition of materials in Table
1 is parts by weight. In the ultrafine nylon fibers-dispersed
polyolefin resin composition (Ny-PO), the polyolefin was
silane-modified polyethylene obtained by mixing 80 parts by weight
of low-density polyethylene [having a melting point of 110.degree.
C. and an MFR of 5.0 (g/10 min.)] with 1.0 part by weight of
.gamma.-methacryloxypropyltrimethoxysilane as a silane coupling
agent, 0.5 part by weight of Irganox 1010 as an oxidation inhibitor
and 0.5 part by weight of d-.alpha.-cumyl peroxide (having a
concentration of 40%) as a peroxide, charging their mixture into a
double-screw extruder having a diameter of 45 mm and heated to
170.degree. C. and kneading and palletizing it. The whole amount of
the silane-modified polyethylene as obtained, 20 parts by weight of
nylon 6 (having a melting point of 215 to 225.degree. C.) as a
nylon component and 0.5 part by weight of Irganox 1010 were kneaded
in a double-screw extruder set at 235.degree. C. and having a
diameter of .phi.3 mm. Die, extruded in a strand form through the
die, and it was cooled by air, taken up in a draft ratio of 7 by a
take-up roll, and stretched to 1.5 times between 5-inch rolls at
room temperature, whereby pellets were obtained. [0095] [Evaluation
of Electric Wires for Properties]
[0096] The electric wires made by the electric wire extruder above
were evaluated for tensile properties (yield, breakdown strength
and elongation), wear resistance and flame retardancy. The test
results are shown in Table 1. [0097] <Tensile Test>
[0098] A electric wire specimen having a length of about 150 mm was
marked in its middle portion with gages having a distance of 50 mm
therebetween, was attached to a chuck in a testing device as
specified by JIS B7721, and was pulled at a pulling rate of 200
mm/min., and its tensile elongation was determined from the maximum
tensile load (MPa) and the length as found between the gages when
it was broken. [0099] <Wear Resistance>
[0100] The test was conducted by using a scrape wear testing device
as shown in FIG. 4. More specifically, an electric wire specimen
111 having a length of about 1 m was placed on a sample holder 105
and fixed by a clamp 104. A plunger 103 provided at its end with a
piano wire 108 having a diameter of 0.45 mm was pressed against the
electric wire specimen 111 at a total load of 7 N by using a
pressing member 101 and reciprocated along it (along a
reciprocating distance of 14 mm) until the insulator on the
electric wire specimen 111 was worn and the piano wire 108 of the
plunger 103 contacted the conductor 106 in the electric wire
specimen 111, and the number of times of reciprocation as completed
until then was determined. [0101] <Flame Retardancy>
[0102] An electric wire specimen 10 having a length of 600 mm or
more was set in an inclined position at an angle of 45.degree. in a
windless tank, as shown in FIG. 5, and a reducing flame was applied
for 15 seconds by a Bunsen burner 20 to it at a point 500.+-.5 mm
from its upper end, and the time after which for the flame to go
out was determined. [0103] [Evaluation for Colorability]
[0104] A coloring solution was prepared by dissolving 3% by weight
of Plast Blue 8580 as a dye in xylene. The coloring treatment of
each electric wire obtained as described before was carried out by
dipping it in the coloring solution at temperatures of 25 and
60.degree. C. for 10 seconds and washing it with xylene.
[0105] The coloration of the electric wire after coloring treatment
was read as image data by a computer and the color density of the
image data was determined in accordance with a gray scale by using
image processing software. The gray scale was for graduating color
density in a range from 0 (black) to 255 (white). The test results
are shown in Table 1.
* * * * *